JPH08188009A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PURPOSE: To enhance durability in an inclined belt layer by eliminating a region where a rubber coated tape becomes one layer at both edges of a corrugated belt layer. CONSTITUTION: A pneumatic radial tire for heavy load has a corrugated belt layer 5 constituted with a spirally winding structure of a rubber coated tape 4 comprising corrugated steel cords actually extending in the circumferential direction of a tire on the outer circumferential side of an inclined belt layer, and formed by applying rubber to a plurality of corrugated steel cords. When the corrugated belt layer 5 is formed by spirally winding the rubber coated tape 4, the rubber coated tape 4 is wound up at least one turn in parallel to the tire circumferential direction around the both edges 10 of the corrugated belt layer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty pneumatic radial tire, and more particularly to a corrugated belt structure having improved durability of an inclined belt layer.

[0002]

2. Description of the Related Art As a conventional technique, the applicant of the present invention has disclosed Japanese Patent Laid-Open No.
There is one as proposed in Japanese Patent Publication No. 183207. In this heavy-duty pneumatic radial tire, a wavy belt layer made of a wavy steel cord extending substantially in the circumferential direction of the tire is provided on the outer peripheral side of the inclined belt layer, and the wavy belt layer is wavy. It is composed of a spirally wound structure of rubberized tape made by aligning and coating a plurality of steel cords with rubber, and the winding start portion and winding end portion of the rubberized tape are respectively from the side edge of the wavy belt layer. Also has a corrugated belt layer positioned on the inner side in the width direction. The corrugated belt layer mainly prevents the inclined belt layer from being lifted up by centrifugal force during running of the tire, and thus prevents shear strain between the inclined belts.

[0003]

However, as shown in FIG. 8, on the outer peripheral side of the inclined belt layer, a rubberized tape 02 formed by aligning and corrugating a plurality of corrugated steel cords is used, for example, as a starting point. When the corrugated belt layer 01 is spirally wound from the point S0 in the tire circumferential direction to reach the end point E0 in the axial direction (width direction) as shown by the arrow, the corrugated belt is formed in a cylindrical shape. When the layer 01 is cut at one position in the axial direction and developed to make it a plan view, it becomes as shown in FIG. Then, in FIG. 9, the wavy belt layer 01 is shown in FIG.
(A) and (b). That is, as is clear from FIGS. 9 and 10, in the regions 04 and 04 indicated by diagonal lines at both end portions 03 and 03 of the wavy belt layer 01, the rubberized tape 02 is not laminated in two layers, and It is a layer. This means that although the wavy steel cords forming the rubberized tape 02 extend substantially in the circumferential direction of the tire, the rubberized tape 02 having a width of about 5 to 30 mm is formed on the wavy belt layer 01. Since the corrugated belt layer 01 is formed by spirally winding over the entire width from one side end portion 03 to the other side end portion 03, the rubberized tape 02 is wound at a slight angle in the circumferential direction. And the rubberized tape 0 at both end portions 03, 03 of the wavy belt layer 01.
A turning point K that changes the axial traveling direction when winding 2
This is because the areas 04 and 04 occur before and after 0 and K0.

For this reason, in the region 04 where the rubberized tape 02 shown by the diagonal lines is one layer, the inclined belt layer formed of at least two inclined belts formed on the radially inner side of the wavy belt layer 01. The tightening force from the outer peripheral side becomes smaller. When the force for tightening the inclined belt layer from the outer peripheral side is reduced in this way, since the steel cords of at least two layers of the inclined belts each made of rubber-coated steel cords intersect each other, the two layers of When the inclined belts try to float due to a centrifugal force, the inclined belts move toward each other in a direction in which the angle becomes smaller with respect to the tire circumferential direction, and the shear strain between the inclined belts becomes larger than the other portions. Therefore, the wavy belt layer 0
The magnitude of the shear strain of the inclined belt layer corresponding to the both end portions 03, 03 of 1 is shown in the graph arranged on the left and right of the wavy belt layer 01 in FIG. Further, there is a problem that the belt peeling occurs in the inclined belt layer relatively early in a portion where the shear strain is large, resulting in failure after running for a long time. Therefore, the present invention is to improve the durability of the inclined belt layer by eliminating the regions where the rubberized tape is a single layer at both end portions of the wavy belt layer.

[0005]

This object is to provide at least a pair of bead cores, a carcass whose end portions are folded back around each bead core and locked, and intersect each other on the outer peripheral side of the crown portion of the carcass. And a wavy steel cord that extends substantially in the circumferential direction of the tire on the outer peripheral side of the tilted belt layer, and further has a wavy shape. A wavy belt layer constituted by a spirally wound structure of a rubberized tape obtained by aligning a plurality of steel cords with a rubber coating, and a tread arranged on the outer peripheral side of the wavy belt layer. The winding start portion and the winding end portion of the pulling tape are located inside the side edges of the wavy belt layer in the axial direction, respectively, and are heavy-duty pneumatic radiators. In a rutile, when forming the wavy belt layer by spirally winding the rubberized tape, when the rubberized tape comes to a side end portion of the wavy belt layer, the rubberized tape is parallel to the tire circumferential direction. This can be achieved by winding the film for one rotation or more and then changing the axial traveling direction to the opposite direction.

[0006]

According to the present invention, when a wavy belt layer is formed by spirally winding a rubberized tape formed by aligning a plurality of wavy steel cords and applying a rubber coating, the side edges of the wavy belt layer are formed. Is configured to wind the rubberized tape parallel to the circumferential direction for one rotation or more. As a result, the area of the wavy belt layer having only one layer of the rubberized tape is extremely narrow at the side end portion. That is, when forming the wavy belt layer as described above, when the rubberized tape is wound around the side end of the wavy belt layer once in parallel with the circumferential direction, only one layer of the rubberized tape is formed. Area is halved compared to the prior art described in FIGS. 9 and 10, and when the rubberized tape is wound two or more times in parallel with the circumferential direction, the rubberized tape has only one layer. The area of is eliminated and becomes even more effective.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view in the width direction (axial direction) of a pneumatic radial tire for heavy load showing a peripheral structure including a corrugated belt layer of the present invention. In the figure, the heavy-duty pneumatic radial tire has at least a pair of bead cores (not shown), and a carcass 1 in which end portions are folded back and locked around each bead core,
Further, the carcass 1 has an inclined belt layer 3 which is disposed on the outer peripheral side of the crown portion and is composed of two inclined belts 2 as an example. Here, these inclined belts 2 and 2 are
10 ° to 70 °, preferably 10 with respect to the tire circumferential direction
These inclined belts 2, 2 extend at an angle of 30 degrees to 30 degrees.
It is formed by rubber coating steel cords that cross each other.

A corrugated belt layer 5 is disposed further on the outer peripheral side of the inclined belt layer 3, and the corrugated belt layer 5 is
It consists of wavy steel cords that extend substantially in the circumferential direction of the tire, and the width formed by aligning a plurality of these wavy steel cords and rubber coating them is 5 to 5
It is a spirally wound structure of a rubberized tape 4 of about 30 mm. The corrugated belt layer 5 is formed by winding the rubberized tape 4 on the outer peripheral surface of the inclined belt layer 3 spirally from the starting point S shown in FIG. To the end point E. FIG. 3 is a plan view in which the corrugated belt layer 5 thus formed in a cylindrical shape is axially cut at one location and developed. 4 is a sectional view taken along the line CC of FIG. 3 and a sectional view taken along the line DD of FIG.
(A) and (b).

3 and 4, when the rubberized tape 4 is wound in the tire circumferential direction, one side end portion 8 and the other side end portion 9 of the rubberized tape 4 are abutted or superposed. While winding in a spiral. For this reason, the rubberized tape 4 is slightly angled in the circumferential direction. However, the rubberized tape 4 is wound forward, and the rubberized tape 4 is wound around the side edges 10 and 10 of the wavy belt layer 5 once in parallel with the circumferential direction. And after wrapping once,
At the turning points K, K, the rubber tape 4 is spirally wound in the axial direction of travel toward the center of the wavy belt layer 5 in the width direction. In the wavy belt layer 5 of the present embodiment thus obtained, the shaded areas 11 and 11 in which the rubberized tape 4 is one layer are different from those of the prior art shown in FIGS. Has been halved. As a result, the magnitude of the shear strain of the inclined belt layer corresponding to the both end portions 10 and 10 of the corrugated belt layer 5 of the present embodiment is shown in the graph of FIG. The magnitude of the shear strain of the prior art shown in FIG. 11 is half or less.

As another embodiment, as shown in FIGS. 6 and 7, the rubberized tape 4 is wound in a spiral shape and is wound at both end portions 10 and 10 of the wavy belt layer 5 in parallel with the circumferential direction. Wrap around. Then, thereafter, at the turning points K, K, the axial direction of the rubberized tape 4 is spirally wound toward the inner side in the width direction of the wavy belt layer 5. Then, as is apparent from FIGS. 6 and 7, in this other embodiment, there is no region where the rubberized tape 4 is a single layer on both side end portions 10 and 10 of the wavy belt layer 5. in this way,
The rubberized tape 4 is attached to both end portions 10, 1 of the wavy belt layer 5.
When it is wound twice or more parallel to the circumferential direction at 0, the effect of tightening the inclined belt layer becomes more effective, and the wavy belt layer 5
The magnitude of the shear strain of the inclined belt layer does not become larger at the both side end portions 10 and 10 than at other portions.

Here, each of the starting point S which is the winding start end and the ending point E which is the winding end end of the rubberized tape 4 is
It is preferably located on the inner side in the width direction of the side edges 12 and 12 of the wavy belt layer 5, and is preferably separated from the side edges 12 and 12 by at least twice the width of the rubberized tape 4.
The steel cord that constitutes the rubberized tape 4 may be formed into a corrugated shape with a swing width of 3 mm and a wave pitch of 32 mm.

In the example shown in FIG. 1, the protective belt layer 6 is arranged on the outer peripheral side of the wavy belt layer 5 and between the tread 7. The protective belt layer 6 is 10 to 70 degrees in the tire circumferential direction, preferably 10 to 30 degrees.
It may extend linearly at an angle of degrees and may be formed of, for example, a steel cord similar to the inclined belt layer 3.

[0013]

As described above, by winding the rubberized tape one or more turns parallel to the circumferential direction of the tire at the side end of the wavy belt layer, it is possible to increase the shear strain of the inclined belt layer. Therefore, the durability of the inclined belt layer can be improved, and tire failure due to peeling can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional view in the width direction of a tire crown portion showing an embodiment of the present invention.

FIG. 2 is a diagram showing a winding order in the axial direction of the rubberized tape in the example.

FIG. 3 is a development view of a corrugated belt layer formed in a cylindrical shape in an example.

FIG. 4 is a sectional view taken along line CC of FIG. 3A and a sectional view taken along line DD of FIG.

FIG. 5 is a diagram showing the magnitude of shear strain in Examples.

FIG. 6 is a development view of a corrugated belt layer formed in a cylindrical shape in another example.

7 is a sectional view taken along the line EE of FIG. 6 (a) and a sectional view taken along the line FF of FIG. 6 (b).

FIG. 8 is a diagram showing a winding order in the axial direction of a rubberized tape according to a conventional technique.

FIG. 9 is a development view of a corrugated belt layer formed in a cylindrical shape according to a conventional technique.

10 is a sectional view taken along the line AA of FIG. 9 (a) and a sectional view taken along the line BB of FIG. 9 (b).

FIG. 11 is a diagram showing the magnitude of shear strain in the prior art.

[Explanation of symbols]

01: Wavy belt layer 02: Rubberized tape 0
3: side edge 04: area S0: start point E
0: End point K0: Turning point 1: Carcass
2: Inclined belt 3: Inclined belt layer 4: Rubberized tape
5: Wavy belt layer 6: Protective belt layer 7: Tread 8, 9, 1
0: Side edge 11: Area 12: Side edge
S: Start point E: End point K: Turning point

Claims (1)

[Claims] 1. At least a pair of bead cores, a carcass whose end portions are folded back around each bead core and locked, and at least steel cords extending to intersect each other on the outer peripheral side of the crown portion of the carcass. A slanted belt layer composed of two slanted belts, and a wavy steel cord extending substantially in the circumferential direction of the tire on the outer peripheral side of the slanted belt layer. A wavy belt layer constituted by a spirally wound structure of a rubberized tape formed by coating, and a tread disposed on the outer peripheral side of the wavy belt layer, further comprising a winding start portion and a winding end portion of the rubberized tape. Is a pneumatic radial tire for heavy load, which is positioned inward in the width direction with respect to the side edge of the wavy belt layer. When the tape is spirally wound to form the wavy belt layer, the rubberized tape is wound around the side end of the wavy belt layer one or more times in parallel with the tire circumferential direction. Heavy duty pneumatic radial tire.